The present disclosure relates to a system and method for increasing the efficiency of fuel burn in internal combustion piston engines by enhancing the level of turbulence in the fuel-air mixture before and after an ignition event.
Internal combustion engines produce mechanical power from the chemical energy contained in hydrocarbon fuel. Internal combustion engines depend upon the process of combustion: the reaction of a fuel, typically with air, although other oxidizers such as nitrous oxide may be employed. As such, the amount of energy or power released from the fuel is a function of the degree of oxidation and, therefore, is consequently dependent on the amount of oxygen available to the fuel during combustion. It is presently understood that as a general principle, the greater the degree of oxidation saturation of the fuel-air mixture, the higher the efficiency of the engine (reflected for example in the gas mileage of an automobile) and the greater the power output of the engine (reflected for example in horsepower).
The most common fuels in use today comprise hydrocarbons and are derived from petroleum. These include the fuels known as diesel, gasoline and liquefied petroleum gas. Most internal combustion engines designed for gasoline may operate on natural gas or liquefied petroleum gases without modifications except for the associated fuel delivery components. Liquid and gaseous biofuels, such as Ethanol may also be used. Some engines may run on hydrogen, however this can be dangerous, and modifications to the cylinder block, cylinder head, and head gasket are required to contain the flame front.
Combustion of hydrocarbon fuels in internal combustion engines has been found to produce several major pollutants including: oxides of nitrogen (NOX); oxides of carbon (CO, CO2); hydrocarbons (HC); and other pollutants subject to oxidation. Carbon dioxide (CO2) is generally considered a non-toxic necessary by-product of the hydrocarbon oxidation process. With respect to carbon monoxide (CO) and hydrocarbon emissions it is understood that increased oxidation during combustion tends to reduce the formation of these compounds by way of oxidation. With respect to NOX emissions, their formation is understood to be largely a function of combustion temperatures. However, it is also presently understood that improved mixing of the fuel and air may tend to reduce NOX formation. In order to reduce the emissions from internal combustion engines directly to the environment, catalytic converters have been employed. Catalytic converters, however, are costly and their effectiveness over time weakens requiring inspection and replacement to maintain performance. Further, the life span of catalytic converters is understood to be a function of the amount of pollutants (primarily unburned hydrocarbons) that the converter has processed. Accordingly, in addition to increasing the efficiency and power output of the internal combustion engine, increased oxidation and saturation of the fuel-air mixture during combustion is also likely to increase the life span of the catalytic converter.
Internal combustion engines require a means of ignition to promote combustion. Most engines use either an electrical or a compression heating ignition system. Electrical ignition systems generally rely on a lead-acid battery and an induction coil to provide a high voltage electrical spark to ignite the air-fuel mix in the engine's cylinders. Compression heating ignition systems, such as diesel engines, rely on the heat created in the air by compression in the engine's cylinders to ignite the fuel. Once successfully ignited and burned, the combustion products, hot gases, have more available energy than the original compressed fuel-air mixture (which had higher chemical energy). The available energy is manifested as high temperature and pressure which may be translated into work by the engine.
Reciprocating and rotary engines comprise two categories of positive displacement engines that are traditionally employed to power motor vehicles. In general, a positive displacement internal combustion engine is an engine in which the flow of the fuel-air mixture is segmented into distinct volumes that are completely isolated by solid sealing elements throughout the engine cycle, creating compression and expansion through the physical volume changes within the chamber. Of the two engines, the reciprocating engine is by far the more common.
Reciprocating engines incorporate a piston that travels back and forth in a chamber formed in the engine block and transmits power through a connecting rod and crank mechanism to the drive shaft of a vehicle. Typically the chamber is cylindrical and is often referred to as a cylinder. A majority of reciprocating engines work on what is known as a four-stroke cycle. That is, each cylinder of the engine requires four-strokes of its piston or two revolutions of the crankshaft to complete the sequence of events which produces one power stroke. The first stroke is termed an intake stroke starting with the piston at top center crank position and ending with the piston at the bottom center crank position. As the piston moves from the top to the bottom center crank position, a fresh intake mixture generally comprised of air or air and fuel is drawn into the cylinder through an inlet valve, which typically opens just before the stroke starts and closes shortly after it ends. Whether the intake mixture drawn into the cylinder is comprised of air or air and fuel is dependent on the type of engine. For example, in a typical spark ignition engine, air passes through an air filter and then is mixed with fuel in the intake system prior to entry to the engine using a carburetor or fuel injection system. The fuel-air mixture is then drawn into the cylinder via the intake valve during the intake stroke. In comparison, a compression ignition engine inducts air alone into the cylinder during the intake stroke and the fuel is directly injected into the engine cylinder just before combustion.
FIG. 1 is an illustration of a common cylinder 10, piston 20 and valve configuration for a four-stroke spark ignition reciprocating engine 100 wherein the cylinder 10 is approaching bottom center crank position during an intake stroke. The inlet valve 30, through which an intake mixture 32 is drawn, is generally comprised of an elongated rod called the valve stem 34 and an integrally connected generally disc shaped surface called the valve head 35. The valve head 35 is manufactured to have a seat 36 that is adapted to mate with the internal edge surface of an orifice or port 38 located usually in the top of the cylinder 10. The outlet valve 40, through which an exhaust mixture is expelled (not shown), is also generally comprised of a valve stem 42 and an integrally connected generally disc shaped valve head 45. Additionally, for a two-stroke engine, there may simply be an exhaust outlet and fuel inlet instead of a valve system.
Increasing the efficiency of fuel burn in internal combustion engines, i.e., improving the rate of conversion of fuel into energy has long been a desirable goal. Many have addressed the issue of improving the mixture of air and fuel in the combustion chamber by increasing turbulence in the mixture during the travel of the piston in the chamber. Exemplary methods attempting to improve the fuel-air mixture include increasing chamber turbulence through the installation of grooves in the compression head of the piston (see, e.g., the Singh U.S. Pat. No. 6,237,579 and the Barnaby U.S. Pat. No. 1,745,884), installation of squish areas and vanes in the piston head (see, e.g., the Nakanishi U.S. Pat. No. 4,280,459), installation of guiding ribs on the crown of the piston (see, e.g., the Wirth U.S. Pat. No. 6,047,592), and grooving the piston crown to create a central squish area with radiating channels (see, e.g., the Evans U.S. Pat. Nos. 5,065,715, 5,103,784, and 4,572,123). The aforementioned examples, however, require significant modifications to either the piston or to the corresponding cylinder or engine and impart a cyclonic turbulence oriented and moving along the longitudinal axis of the cylinder, i.e., the thrust line of the piston (the direction of the thrust line of the piston is referred to as the “axial” direction throughout the present application).
Others such as that disclosed in the Showalter U.S. Pat. No. 4,471,734 seek to increase the efficiency of fuel burn by interrupting the symmetry of the roll-up of fuel-air mixtures occurring as a result of symmetrical cylindrical geometry. By placing uneven edges at the circumferential boundary of a piston crown, Showalter interrupts roll-up vortices aligned along the line of thrust of the piston. Still other attempts to address the issue of increasing the efficiency of fuel burn include installations of an entire piston crown having a spirally notched extension to facilitate a generally cylindrical expanding flame front over the top of the piston during a power stroke (see, e.g., the Hansen U.S. Pat. No. 5,000,136) and installation of a piston crown having both a squish area and guiding ribs thereon (see e.g., the Simay U.S. Pat. No. 4,669,431). Such examples also require significant modifications to either the piston geometry or to the engine block or head and impart a cyclonic turbulence oriented and moving in the axial direction (i.e., the sliding or reciprocating axis of the piston).
The method and device of the present subject matter, in various embodiments, provides for the highly desirable characteristics of enhancing the turbulence in the fuel-air mixture before and during the ignition event while avoiding significant modifications to either the piston geometry or to the engine block or head. Further the method and device of the present subject matter increase oxidation saturation of the fuel-air mixture by creating significant turbulence in the combustion chamber before the ignition event and during flame front propagation from that event. As distinguished from the prior art where vortices may be generated in the chamber that are aligned with the axis of movement of the piston, the devices and methods of the present disclosure creates turbulence in the combustion chamber by the generation of vortices in the fuel-air mixture having a movement that is more lateral than axial relative to the axis of movement of the piston during piston travel within the chamber. A vortex may be broadly defined as a whirling mass of air, flame, or fuel-air mixture having a tangential velocity component perpendicular with, and not intersecting the central axis thereof, i.e., forming a three-dimensional column or spiral having a generally central axis. As used herein, the orientation of a vortex is generally the direction of the central axis of the vortex (i.e., the vortex line), and a directional adjective (e.g., “radial”) modifying the term “vortex” indicates the general orientation of the central axis of the vortex.
In one aspect the method and device of the present subject matter increases the efficiency of fuel burn in piston engines by enhancing the level of turbulence in the fuel-air mixture before an ignition event and increases the efficiency of the conversion of fuel energy to work by residuary influences of turbulence on the post ignition flame front. Thus, embodiments of the present subject matter promote a more rapid and complete burning of the fuel, lower engine operating temperatures, and enhanced torque and power through the range of engine operation resulting in an improved fuel economy having lower emissions, smoother operation, increased combustion pressures, and an increased engine life.
Accordingly, it is an object of the present subject matter to obviate many of the deficiencies of known internal combustion engines and to provide a novel internal combustion engine having a piston reciprocatingly slidable within a combustion chamber to compress for combustion a fluid mixture including oxygen and a combustible fuel, and to provide driving power in response to the combustion of the fluid mixture within the chamber. The surface of the piston in contact with the fluid mixture causes vortices in the fluid mixture as the piston moves axially within the cylinder and the orientation of one or more of the vortices created within the fluid mixture relative to the sliding axis of the piston is more lateral (e.g., radial in a cylindrical chamber) than axial.
It is another object of the present subject matter to provide a novel internal combustion engine having a piston reciprocatingly slidable within a combustion chamber to compress for combustion a fluid mixture including oxygen and a combustible fuel so that driving power is provided in response to the combustion of the fluid mixture within the chamber, wherein the surface of the piston in contact with the fluid mixture includes a plurality of vanes extending from the piston generally axially of the chamber and extending generally from the center of the piston outwardly toward the radial periphery thereof. In preferred embodiments, each of the vanes possess two generally axially extending walls and a connecting surface at the distal end thereof to the piston, and the slope relative to the sliding axis of the piston of one of these two walls is greater than the slope of the other of these two walls.
It is also an object of the present subject matter to provide a novel device for attachment to the crown of a piston of a reciprocating piston engine for causing vortices in the fluid contained in the combustion chamber during reciprocation of the piston in which the orientation of one or more of the vortices is more orthogonal than parallel to the reciprocating axis of the piston.
It is an additional object of the present subject matter to provide a novel device for attachment to the crown of a piston in a reciprocating piston engine, more specifically, a device having an axially central portion and a plurality of vanes extending radially outwardly from the central portion in which the slope relative to the reciprocating axis of the piston of one of the axially extending walls of the vanes is greater than the other.
It is still another object of the present subject matter to provide a novel reciprocating piston engine wherein the movement of a piston within a cylinder creates vortices in the fluid within the cylinder in which the orientation of the vortices relative to the cylinder is more radial than axial.
It is an object of the present subject matter to provide a novel piston for reciprocating in a combustion chamber for creating radial vortices of the fuel-air mixture compressed within the combustion chamber by movement of the piston axially within the chamber.
It is a further object of the present subject matter to provide a novel radial vortex generator adapted for attachment to the crown of a piston comprising a plurality of vanes extending from the crown generally axially of the piston from the radial center thereof toward the radial periphery thereof.
It is still a further object of the present subject matter to provide a novel method of generating combustion enhancing turbulence in the fluid within a combustion chamber of a reciprocating piston engine.
It is also an object of the present subject matter to provide a novel method of generating combustion enhancing turbulence in the fuel mixture in the combustion chamber of a reciprocating piston internal combustion engine by creating vortices in the fuel air mixture in which the orientation of one or more of the vortices relative to the reciprocating axis of the piston is more lateral than axial.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the preferred embodiments.